Structure and principle of mining backhoe loader Encyclopedia of coal mining backhoe loader
May 05 , 2022

Mining loaders are mechanical equipment, mainly used for various mines, hydropower, tunnel projects such as phosphate ore, iron ore, copper ore, gold ore, silver ore, lead-zinc ore, coal mine roadway, etc. The collection and transportation of gravel and soil materials for construction and loading.

It is a production device that is combined with a manipulator and a conveyor, and combines the functions of slag removal and conveying and loading into one. It adopts an electric full-hydraulic control system. It is an indispensable advanced mining equipment for mining enterprises and a substitute for labor and other machinery.
The product implements the standards of JB/T5503-2004 "Vertical Claw Backhoe Loader" and Q/DK01-2009 "Coal Mine Backhoe Loader". Environmental conditions for mining backhoe loaders:
1) The slope of the roadway is not more than 15°;
2) The ambient temperature of the roadway is -5℃~+40℃, and the maximum relative humidity is not more than 90% (when the temperature is 25℃);

3) The altitude of the site of use does not exceed 1000m. When using it in a plateau environment with an altitude of more than 1000m, necessary measures should be taken or special design should be carried out according to the situation; 

4) The maximum size of the loaded rock blocks should not exceed 400mm;

5) The voltage limit deviation is +5%. AC frequency limit deviation is ±1%;

6) The content of coal dust and methane explosive gas around the loader should meet the safety content stipulated in the coal mine safety regulations.

Structural features and working principle
Overall structure, working principle, working performance
The mining backhoe loader is mainly composed of three major mechanisms of driving, digging and conveying, and two hydraulic and electrical systems. Through the coordination and cooperation of various parts, the hydraulic and electrical actuators and mechanical transmission mechanisms will finally realize the specified actions and complete the operation process.
This machine integrates four performances: hydraulic walking, excavation and collection, transportation and loading. Among them, the hydraulic walking function is to drive the front and rear wheels through the hydraulic motor. The hydraulic motor has three functions: forward, backward and automatic braking; the four-wheel drive has the characteristics of ground force and strong driving force.
The excavation and collection function is completed by the manipulator, which has the functions of excavating, extending
Arm, loading and unloading performance, the boom can be raised, lowered, left and right slew, the manipulation of excavation and collection is controlled by full hydraulic pressure, controlled by six operating handles, each handle controls two actions, a total of twelve actions. The conveying and loading performance is completed by the conveyor system. The conveying frame is controlled up and down by the hydraulic cylinder. When the conveying frame is lowered, the front wheel can be supported. At the same time, the front receiving port of the conveying frame and the ore contact surface are closer, and the working stability is better. Strong, at the same time, it can collect bulk materials and level the site. The width of the conveyor belt is 650mm, and the conveying speed is about 5m/s. The conveyor belt is driven by a hydraulic motor to drive the rollers, which makes the conveyor performance more stable and has a longer service life.
The hydraulic system of the whole vehicle is powered by a 15kw motor to drive a dual high-pressure gear pump. The hydraulic oil is input into a multi-way reversing valve through the gear pump, and the control of each hydraulic device is realized through the operating handle.
The electrical system of the whole vehicle adopts mine explosion-proof electromagnetic starter to realize the control of the motor and ensure the safety of people and equipment.
The power source of the machine is the power frequency 660 (380) V three-phase AC power supply introduced from the outside. The whole machine adopts a 15kw motor, and the driving drum is hydraulically driven, and only one person is required for operation.
running gear
The traveling mechanism of this machine is composed of chassis, front axle, rear axle, tires, hydraulic motor, steering cylinder, etc.
Working principle: External three-phase 660 (380) V power supply, control the oil pump through the electric control button, use the multi-way valve handle to control the hydraulic motor, the motor drives the transfer case, and the transfer case drives the front and rear axles to rotate, thereby driving the tires walk. This machine does not need an independent brake stop system. When parking on a slope, you only need to set the multi-way valve travel control to the neutral position. At this time, the hydraulic system makes the front and rear wheels in a locked state and cannot be reversed; when parking for a long time is required When the lift groove is lifted, the front shovel is on the ground to realize parking.
Working Organization
The working mechanism of this machine is composed of a boom seat, a boom cylinder, a boom, a forearm, a bucket, a boom cylinder, a forearm cylinder, and a bucket cylinder.
Working principle: The oil pump works, and the multi-way valve handle is used to manipulate the boom, stick, and bucket to complete various functions such as ascending, descending, forward extension, retraction, rotation, and excavation. Controlling the expansion and contraction of the rotary oil cylinder can make the boom rotate left and right, and one-way throttle valves are installed at both ends of the rotary oil cylinder to control the speed of rotation. Controlling the telescopic boom of the boom cylinder can make the boom move up and down. One end of the boom cylinder with the rod cavity is equipped with a one-way throttle valve to control the descending speed of the boom. Controlling the extension and retraction of the forearm cylinder can make the forearm move back and forth. Controlling the expansion and contraction of the bucket cylinder can make the bucket perform digging action. The bucket is equipped with bucket teeth, which can be replaced after wear
The conveying mechanism of this machine consists of a front shovel, a driven roller, a roller, a carrier and a conveyor belt.
Working principle: External three-phase 660 (380) V power supply, start the motor through the mine explosion-proof electromagnetic starter, and use the multi-way valve handle to operate the hydraulic motor to drive the roller to realize the rotation of the conveyor belt and achieve the continuous conveying function.
Hydraulic system
The hydraulic system equipment of this machine is composed of steel ball hydraulic motor, gear pump, priority valve, multi-way reversing valve, hydraulic steering gear, hydraulic cylinder, hydraulic support hose, radiator, return oil filter, hydraulic oil tank and cable. The hydraulic hose has a safety mark certificate when it is used, and it is within the validity period.
The working cycle process of the hydraulic system is shown in Figure 6 (the black lines and arrows are the oil inlet pipe and the oil inlet flow direction, and the blue lines and arrows are the oil return pipe and the oil return flow direction): through the hydraulic oil pipe, the hydraulic oil tank, hydraulic pump, phase After connecting in series with multi-way reversing valve, and hydraulic steering gear cylinder, multi-way reversing valve and bucket oil cylinder, boom oil cylinder, stick oil cylinder, conveying frame oil cylinder, hydraulic motor, one-way valve and rotary seat oil cylinder They are all connected with hydraulic oil pipes; the steering gear, multi-way reversing valve and priority valve are all connected with the oil return main pipe through the oil return branch pipe; the oil return main pipe is connected in series with the hydraulic oil radiator, hydraulic oil filter and hydraulic oil tank.
The hydraulic oil pump runs synchronously with the motor through the shaft, starts the motor, and the gear oil pump starts to work, sucks the hydraulic oil from the oil tank, and the pumped hydraulic oil enters the multi-way reversing valve and the hydraulic steering gear to prepare for driving and operation.
During operation, when any one of the valves is pulled to a certain working position, the slide valve will cut off the neutral position channel and open the two cavities of the valve body at the same time. The low-pressure oil in the other chamber of the cylinder passes through the other side of the valve
The cavity is cooled by the filter and hydraulic oil and returned to the fuel tank. If the valve stem is pulled to the opposite position
set, repeat the above process in reverse.
The rated working pressure of the loader is 12Mpa. If the load is too large during operation, the safety valve of the distribution valve will automatically open, and the high-pressure oil will directly return to the oil tank through the oil return pipe to prevent damage to hydraulic components, pipelines and components.
Working principle: External three-phase 660 (380)V power supply through explosion-proof explosion-proof magnetic starter
Operates electric motors, explosion-proof lights, and electric bells. This machine adopts
Dual magnetic starters, one controls the main oil pump and the other controls the belt conveyor motor.
Installation, commissioning and installation
The installation of the loader must be carried out by professionals. According to the structural characteristics of the whole machine, install it according to the requirements of the drawings. Follow the installation sequence of chassis frame - conveying frame - adjusting frame - excavation part - hydraulic system - electrical system.
1. Preparatory work before trial operation: confirm that the circuit is connected and the cable is properly tight; confirm that the oil tank has been filled with hydraulic oil as required; apply grease to the joints of the connecting parts and the joint surfaces of the cylinder parts.

2. Trial operation: First start the walking system to check whether the machine is running normally, whether the steering system is flexible, and then start the conveying system to see if the operation is normal. 

Next, start the excavation part to check whether the extension arm is normal and whether the extension arm rotates flexibly.

Assembly Precautions
1. When assembling each connecting bolt, check whether the anti-loose washers are complete and whether the tightness meets the requirements.
2. The joint part of the hydraulic system must be wiped clean, and no dust and impurities can enter. At the same time, check whether the sealing ring is complete or damaged, and all pipelines should be straightened and fixed according to their original positions.
3. After the installation of the whole machine, carefully check the parts, fittings, accessories, etc., whether the installation is correct and secure.
4. Special personnel should be responsible for the installation of electrical components. The diameter of the cable entering the junction box should be consistent with the diameter of the rubber pad. When pressing the terminal head, there should be no gap between the rubber pad and the cable and between the rubber pad and the junction box, otherwise the explosion-proof performance will be lost.

use, operate

Inspection before work:
1. Check the power supply system: the cables and connectors should be in good condition without damage; the connection lines should be in good condition, without burning damage or looseness.
2. Check the hydraulic system: The connection between the components of the hydraulic system and their connecting pipelines should be tight, and there should be no obvious leakage; the hydraulic oil level should meet the regulations (the oil volume accounts for about 4/5 of the total volume of the fuel tank) .
3. Check the control system: each control handle should be in a neutral position, and the control should be flexible without sticking.
4. Check the conveyor system: the conveyor belt should be in good condition and the tension is appropriate; the rollers and drums should rotate flexibly, and there should be no abnormal sound.
5. When you need to stop the brake during walking, put the foot valve in the neutral position, that is, brake. If you stop for a long time, you need to press the head board to the ground. 6. When the loader is walking or reversing, the electric bell should be started as a warning signal.
Description of the specific operation process
1. Operation while walking:
Turn on the three-phase power supply; press the starter, the main oil pump moves, the main motor starts to work, drives the gear pump to rotate, the hydraulic oil starts to work from the oil tank through the pump to the multi-way reversing valve, and the return oil is filtered from the oil return pipe through the hydraulic oil. The hydraulic oil radiator and hydraulic oil radiator flow back to the oil tank.
Push and pull the first handle of the left hand to the right or left, and the shovel mouth is raised or lowered through the action of the multi-way reversing valve to convey the lift tank action.
Push and pull the second handle of the left hand forward or backward, and the hydraulic motor rotates and drives the wheels to rotate through the multi-way reversing valve, so as to realize the forward or backward of the whole machine; at the same time, the steering wheel is manipulated to change the driving direction of the whole machine through the hydraulic steering gear and the direction cylinder. .
2. During mining operations:
Main operation methods: lifting the boom, lowering the boom, turning the arm to the right, turning the arm to the left, lifting the forearm, and dropping the forearm; use the bucket, forearm, and boom to pick up the ballast into the transport trough, and then the belt conveyor will The slag is transported to the side dump truck or other ore transport equipment.
1. The user must be familiar with this manual, and operate and maintain in strict accordance with this manual. It is the user's responsibility to carry out illegal operation, use and maintenance not in accordance with the requirements of this manual, resulting in vehicle damage or personal injury.
2. The vehicle must be operated by special personnel, and non-operators are not allowed to drive or move indiscriminately. The bucket should be on the ground during non-working hours, and it is strictly forbidden to park it in the air. 3. Before operation, it is necessary to check whether the three-phase power supply is balanced, and the voltage of each phase should indicate normal (380V), and it is strictly forbidden to start the motor without a phase.
4. No-load operation and no-load operation must be carried out before operation. The operation can only be carried out when the oil temperature is not lower than 20°C. If the oil temperature is higher than 80°C, the cause should be investigated.
5. The operator should memorize the action of each handle. To achieve the control by hand, the line of sight should be focused on the scooping bucket. When pulling the handle, the action should be stable to avoid hydraulic shock and damage to components and structural parts.
6. During operation or debugging, it is strictly forbidden to stand within the range of the bucket, and it is forbidden to touch the rotating parts. If there is a fault or there is abnormal noise, it should be stopped immediately for inspection, and the main power supply should be cut off.
7. It is strictly forbidden to adjust the pressure of the safety valve without permission, so as not to damage the hydraulic components or affect the performance. If you adjust the working pressure without permission, it is an illegal operation. 

8. When the joystick is stuck, do not operate it hard, and check to eliminate the stuck phenomenon.
9. The hydraulic system should use the corresponding type of hydraulic oil in different seasons; the hydraulic oil should be replaced regularly, the first 200 hours, and every 1000 hours thereafter.
10. The gear oil of the rear axle should be replaced regularly, 50 hours for the first time, and every 500 hours thereafter.
11. Special attention: When the conveyor rack is raised and people carry out maintenance work under the conveyor rack, there must be reliable safety support under the conveyor rack to prevent the conveyor rack from falling suddenly and hurting people.
12. Safety requirements for the power supply: When the power supply is connected, it is necessary to prevent damage to people caused by leakage.
13. Special attention: the state of the fixed position of the connecting shaft sleeve on the transmission shaft between the rear axle and the reduction box, when external force is required to drag the machine, the connecting shaft sleeve must be disengaged; when the machine is working, the connection must be The shaft sleeve is reset, and the fastening screws are tightened to fix it.
14. Portable methane alarm instrument should be equipped when used underground.
15. When working (walking) uphill (downhill), the gear shift should be carried out in a static state, and the tire (or front) should be placed on sleepers to prevent slippage and safety accidents. Maintenance
Disconnect the power supply, and pull the operating handles and pedals to unload the hydraulic system. 

(1) Shift maintenance requirements
First. Check whether the cables and connectors are damaged, whether electrical appliances such as magnetic starters and their connecting lines are burnt or loose, and repair and replace them in time. 

2. Check the lubrication parts such as universal joints, rotating shafts, bearings, etc., and add lubricating oil and calcium-based grease in a correct and timely manner (once per shift). 

3. Check the oil level of the hydraulic oil tank, and refuel if it is insufficient. Check whether there is oil leakage at the connections of the oil pump, oil cylinder, distribution valve, oil pipe, etc. 

4. Check whether each oil pipe is bent and twisted, which affects the smooth flow of the pipeline, whether there is leakage, and remove it in time.
5. Check the connecting parts, whether the fasteners are loose or missing, and fasten them in time.
6. Carry out the cleaning of the whole machine, especially the removal of dust on the radiator.
Second, Month Maintenance Requirements
1. Check the fixing bolts of the oil pump, and tighten them if they are loose.
2. Check the seals of various hydraulic components, especially the "О" type sealing ring of the cylinder piston rod is damaged, if any, it should be replaced in time. 3. Clean the hydraulic oil filter and radiator.
4. Check the hydraulic oil tank, clean up oil stains, remove impurities, and add enough hydraulic working oil.
Third, quarter maintenance requirements
1. Clean the hydraulic system, take samples to check whether the hydraulic working oil is deteriorated, otherwise replace the new oil 

2. Check whether the pressure of the safety valve of the distributor has changed.
3. Check whether the pins and bushings of each part are damaged.
4. Check whether the mounting bolts of the slewing mechanism and its various parts are loose.
5. Replace the necessary wearing parts.
transportation and storage
1. Lifting and transportation from the factory
The loader is transported by road, and the machine can be lifted directly to the trailer with a crane or a crane. The front and rear tires should be padded with triangular sleepers, and the tires of the loader should be tied to the appropriate position of the trailer with ropes.
2. Hoisting and transportation to the mine face, underground installation and precautions
According to the situation of the mine head, the inclined shaft can directly enter the operation; the vertical shaft must be disassembled and hoisted into the mine. The whole machine can be disassembled according to the four parts of the chassis, the conveying frame, the adjusting frame and the excavation part assembly. When disassembling the machine, make a mark in a certain order, and wrap the disassembled hydraulic oil pipe joints to prevent dust from entering. The disassembled parts and components are slowly lifted into the well with a winch, and then installed in the underground in the reverse order of disassembly. It is necessary to ensure that the positions of the components are accurate and the connection is firm and reliable.
3. The loader should be stored in a place with rain-proof and sun-proof facilities, and the rust-proof treatment should be carried out after storage for more than six months.

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